The present invention relates to an improvement in an outboard motor, and in particular to a structure for cooling an AC generator provided to an engine of the outboard motor.
Outboard motors include engines, auxiliary devices disposed in the vicinity of the engines, and engine covers covering the engines and the auxiliary devices. Within the engine covers, there are also disposed AC generators.
The engines have vertically extending crankshafts. Cylinder heads, intake systems, and exhaust systems are disposed in rear parts of space formed within the engine covers. The AC generators are provided in front of the engines.
The crankshafts drive the generators by transmitting their motive powers thereto by means of belts and pulleys extending around the belts.
The outboard motors discussed above are known from, for example, Japanese Patent Laid-Open Publication No. HEI 6-33790. A generator disclosed in the publication is disposed adjacent a front part of an engine. The generator undesirably emits heat when producing electricity. The generator and its associated electronic devices are adversely affected by the heat produced by the generator. The generator needs to be cooled down.
Belts and pulleys extending around the belts to drive the generator are unavoidably positioned above the engine because a crankshaft of the engine is oriented vertically. This requires the generator to be positioned at a high level in front of the engine. An engine cover is disposed to cover upper parts of the engine and the generator. The generator and the engine cover have only a very small space formed therebetween.
The generator thus arranged can be cooled down with decreased efficiency. It has been propose to provide a large space between the generator and the engine cover. However, providing such a larger space increases a height of the engine cover. The outboard motor having such an engine cover of increased height is undesirably rendered large in size.
An object of the present invention is to provide an outboard motor including a generator-cooling structure disposed in a small space formed above a generator of the outboard motor, such that the generator is advantageously cooled down.
According to one aspect of the present invention, there is provided an outboard motor comprising: an engine having a vertically extending crankshaft; an AC generator disposed adjacent the engine; a cooling air guide member disposed above the engine, the cooling air guide member having an opening formed at a portion thereof opposed to the AC generator; and an engine cover covering the engine, the AC generator, and the cooling air guide member.
The generator-cooling structure is disposed above the generator. The structure has the opening formed at a portion thereof opposed to the generator. Air for cooling the generator flows through the opening to cool the generator.
In a preferred form of the present invention, the cooling air guide member is recessed to form a space extending in a front-and-rear direction of the outboard motor, and the cooling air guide member includes a bottom part having the opening formed therein. In a further preferred form of the present invention, the AC generator is disposed adjacent a front part of the engine. Preferably, an outboard motor further comprises an air intake silencer disposed above the engine, the air intake silencer extending in a front-and-rear direction of the engine and having the cooling air guide member attached to a front part thereof.
The structure is recessed to form the space extending in the front-and-rear direction of the outboard motor. The structure includes the bottom part having the opening formed therein.
The structure of recessed configuration provides the space or a duct-shaped passage way through which the air for cooling the generator flows, even if the former is positioned in a small space between the generator and the engine cover. This arrangement eliminates the need for an engine cover having a height larger than required. It therefore becomes possible to render the outboard motor compact. It also becomes possible to provide an improved freedom to design the outboard motor.
Since the structure is attached to the front part of the silencer disposed above the engine, there is no need to provide the engine with particular components such as stays for attaching of the structure to the engine. This facilitates providing the structure to the outboard motor.